Any test meters to check amp draw from vehicle batteries?

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Old 03-04-09, 05:07 PM
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Any test meters to check amp draw from vehicle batteries?

I have a piece of equipment that runs on 2 12 volt =24 volt batteries. The run time has gone from 3 hours down to 1/2 hour, when it now runs out of juice!

We took them out and had the place of purchase (11 month old batteries only) check them and they said they load test just like brand new. (Also note that these are acid batteries, and we have not had to add one drop of water to any of the cells, even though this machine is used a lot and recharged often. And also note that the built in charger charges to over 15 volts and upon completion of the charge, the batteries are at just above 14 volts, but that reading trickles on down some, over time, as it tries to get back to 12.6 volts. To me that all seems normal and good.)

Then we took it to one of the large national chain auto parts stores and they tested them and said they are good, also.

So now it sounds like either there is a drain to ground -or- for some reason one of the two motors is consuming more amps than they used to. Yet the machine runs and sounds like normal according to those who use it. It just does not last, that's all.

These batteries are each marine deep cycle batteries, like the original batteries, and are rated at 120 amp hours (20 more amp hour rating than the original equipped batteries that lasted 3 hours!) The piece of equipment pulls about 36 amps, according to the rating plate, and also when adding up the watts listed for each motor, that is about correct.

I noticed that when I rehooked up the jumper cable between + and -, that I got some small sparking, even with the 2switches to the machine turned off, and the built in charger unplugged. Is it normal to get this spark when completing the 24 volts by putting on that jumper after the other wires were already hooked up to the other + and -?

Does anybody make a test meter for DC batteries to be able to check amp draw when it runs, to see if it is higher than what the motors say on their rating plates?

And would a test with a volt meter, put in series between a battery post and a wire that was hooked up to it prove some sort of short if I got any kind of volt reading while the switches were turned off and the machine were unplugged?

Note that this is truly a 24 volt battery machine. No a/c-d/c inverter system is used. The motors are rated at 24VDC.
 
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Old 03-04-09, 05:54 PM
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Old 03-04-09, 06:35 PM
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$223!!

Anything else not quite as fancy, but gets the job done?
 
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Old 03-04-09, 06:46 PM
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Does this happen to be a floor machine?

You say it is a marine deep cycle battery.

My experience with batteries that are labeled as marine/deep cycle is that they are not a true deep cycle.
They have the ability to withstand both a high starting draw and can be discharged continuously without damage but do neither job very well.

If this is what you have then look into getting a true deep cycle.

Here is one company that specializes in commercial batteries.
 
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Old 03-05-09, 05:40 AM
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amp meters can be expensive especially if its rated for higher amperage reading like the one posted that clamps on a cable.
while a cheaper meter may only be able to read lower amps usually 10 amps max before it blows a fuse.
a simple test light can tell you if you have any draw on the battery by disconnecting one cable and hooking the test light inline if it lights there is some sort of draw on the batteries not sure this would help that much as some electronics could cause a draw on the battery under normal operation.
what type of a piece of equipment is this? as you may be able to track down a draw with out using an amp meter you should probably also check all cables to make sure they are good and have a good connection.
 
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Old 03-05-09, 04:28 PM
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A floor scrubbing machine with only 2 motors. (Not self-propelled as some, so no motor for that.)

In the dark, neither motor sparks inside where the brushes are, and they only get mildly warm at worst. Factory rep today said this floor scrubber has no service bulletins/no history of these motors ever failing. Especially one from 2005.

He is likewise perplexed. He said to fully charge the batteries, is what I did, then run the machine 10 minutes for the sake of testing the battery with a hydrometer. I did so. In fact I just got back from there. I get an upper fair reading (near the bottom of where the good line starts) on each cell. No strong in-the-good readings. Readings on every cell quite uniform. Oddly, when I dunked the hydrometer in a few cells 3 times, one reading was med-high fair, the next was way up into the good, and the last reading was upper fair. ???

In summary: Batteries were new 11 months ago. Batteries hooked up correct from get go, to create 24+ volts, and onboard digital display confrims this. Charger set correct for acid batteries, not gel type. Charger puts out about 15 volts per battery, confirmed with test meter on battery posts. My voltmeter after words says the batteries are over 14 volts. Not a bit of water loss in 11 months. Old batteries lasted 3 hours: These last 1/2 hour -3/4 hour!! The scrubber brush motor and the squeege vacuum motor sound like new/no sound of bogging (from say bad armature, brushes, bearings or hair wrapped around any shafts). No sparking. No extra weight on the scrubber pad as the machine uses gravity only on the 'head'/non-adjustable. Not likely the automatic machine kill switch when battery gets down to 80% charge either, since when the yellow indicator light comes on the machine, that indicates batterry getting low, and machine will soon shut off on red light, you THEN can hear the scrubber motor slow. So the machine really IS running down, as opposed to being falsely told that. (UNLESS - there is some 'brain-board' that controls this - and this all is part of the shutting down process. I may have to call back that tech tomorrow and ask him if an onboard brain box is capable of doing this in order to spare wrecking the motors and is falsely shutting down the machine prematurely. Never thought of that til this second.

The commercial industrial supply place where we bought the scrubber -the tech still thinks regardless of what I was told by the two places that tested the batteries, that something IS wrong with those batteries, becasue he confirmed what the janitor told me, that the old batteries used water and the new ones never have. The tech said that indeed we should have had to periodically add water -and we have not had to. They are all completely full.

Tech confirmed this machine WILL(is supposed to) run for at LEAST 3 hours. And factory equipped batteries are 100 amp hour batteries. The ones we have in there are 120 amp hours !with total (2)motor draw at about 36 amps.
 
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Old 03-05-09, 07:31 PM
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To specifically answer your original question, yes, there is a meter that will measure the current capacity of a battery.

Click image:


Image courtesy of batterymart.com

I just today ordered one like this for work.
I have been using my personal battery tester that looks like the one below but it is not good for small emergency light and fire panel batteries.


Image courtesy of batterymart.com

Either type of tester will work on an auto sized battery to give you an indication of the batteries capacity after it has been fully charged.

You did not answer my question about your battery possibly being one that is tagged as a marine/deep cycle battery............Is it?
If so it could explain its poor performance.

I know what you are up against with rechargeable batteries!

Tomorrow I am bringing my tester to work to confirm that two 12v batteries are bad in an old Advance 200 push scrubber.

To help keep me on my toes in the hospital I work at we have two ride-on and two push scrubbers along with a battery palette jack, several fire panels, emergency lights, patient lifts, and medical equipment all with rechargeable deep cycle batteries.

Oh ya, and computer UPS's, fridges and incubators with alarms, back up batteries for card access and others I just can't think of right now.

What is the make of your batteries and the model number?

And another thing.
If there has been any changes to the flooring, the type of pads on the scrubber or the cleaning solution it could have a bearing on the force needed to spin the pad(s).
 
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Old 03-05-09, 09:53 PM
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Sounds like your problem could be a parasidic amp draw issue. Since you're familiar of the sound of the scrubber and vacuum and neither of them have a odd or laboring sound, we can assume the motors are not pulling excess amps when operating. The spark you're getting when hooking up the battery cable should be the avenue to explore. A relatively inexpensive multi-meter hook up in series (with the leads and knob set the in the proper location) should be able to detect parasidic amp draw.

Or try this, check the battery voltage after fulley charging the batteries. Without using the machine, check the voltage at the batteries every couple hours or overnight. If the voltage is slowly dropping through out the day or over night without using the scrubber, you definately have a parasidic amp draw problem.

Here's another option to try. It sounds like there's only two motors on the scrubber. One for the brushes and one for the vacuum. With the battery cable disconnected, disconnect one motor at the time then re-connect the battery cable. See if the spark still exist or goes away with any one motor disconnected. That could point you in which motor is causing the parasidic amp draw.

Good luck
 
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Old 03-06-09, 02:05 PM
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I have an automotive tool which i paid $8 or $12 for. I forget which. I got it from a local auto parts place.
Just hold it up next to the starter cable or generator wire and it reads the amperage.
Looks real simple inside. Dont know how accurate it is but I think it is close for diagnosis.
Tha alternator out put has a 0 to 120 amps plus and minus
The starter current scale goes from 0 to 400 amp plus and minus.
I looked on the net and I can not find it or one comparable.
Maybe the auto parts store in your area will have them and be able to order the amp range you want for a resonable dollar.
 
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Old 03-06-09, 06:25 PM
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CandiMan,

Here is the short term problem: The after-charging volt reading per battery is over 14 volts. It trickles down to ? I ran this by the dealer and he said that is normal. I have not had the chance yet, to have the machine be charged, and go unused long enough, to see if say it ever dips to below 12.6 volts, for example.

But get this: When I unhooked the red and black wires and ohms tested them, with the switch off (is how the machine sits, naturally), I got no reading, which should mean there couldn't possibly be a leak.

I got 2 new replacement batteries for free today. Installed them and ran the built-in charger. The janitor is going to let me know how long the run time is tonight.

I will keep you all updated here.
 
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Old 03-06-09, 06:34 PM
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frankiee,

Since I like tools and gadgets anyway, I'm going to check that out.
 
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Old 03-06-09, 06:44 PM
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Originally Posted by GregH View Post
You say it is a marine deep cycle battery.

My experience with batteries that are labeled as marine/deep cycle is that they are not a true deep cycle.
They have the ability to withstand both a high starting draw and can be discharged continuously without damage but do neither job very well.

If this is what you have then look into getting a true deep cycle.

Here is one company that specializes in commercial batteries.
Hmmm. Well I'll be! Yes, that is what we have and you are the only one to come up with that explanation. Hmmm. The Advance floor scrubber (yes, that is what we have, too !!! But it is the 20B model) came equipped with Trojan deep cycle batteries - but I do not believe they had the word marine slashed with deep cycle. Hmmm. You may very well be on to something here! That would be something if you are right!

I will look into those tools, you showed pics of. And thanks for your lengthy subsequent reply.

And good luck with YOUR Advance.
 
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Old 03-06-09, 06:50 PM
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Originally Posted by GregH View Post
What is the make of your batteries and the model number?

And another thing.
If there has been any changes to the flooring, the type of pads on the scrubber or the cleaning solution it could have a bearing on the force needed to spin the pad(s).
1. I'll post that when I get back to the batteries.

2. No changes. Also no sound of motor drag. And water comes out for the pads good, so there is no extra friction slowing down the motor. The vac sucks good too.
 
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Old 03-07-09, 04:49 AM
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We had Trojan batteries in a Windsor company Chariot model ride-on scrubber that failed due to housekeeper abuse.
I replaced them with comparable batteries from East Penn that were quite a bit less expensive than the Trojan.

What I have learned is that it is better to deal directly with a battery supplier that carries a wide range of batteries than an automotive parts retailer.
It has been my experience that auto parts retailers really do not have a good understanding of the different battery types.

The East Penn replacement is a DC27 battery for our Advance unit.
If you look at the spec sheet you will see that they have a "12-VOLT DUAL PURPOSE STARTING/DEEP CYCLE SERVICE" battery and a "12-VOLT MARINE/RV HEAVY-DUTY DEEP CYCLE SERVICE (INCLUDING STARTING)" available.
It is likely the first one that you got.
 
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Old 03-08-09, 01:55 PM
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Originally Posted by GregH View Post
We had Trojan batteries in a Windsor company Chariot model ride-on scrubber that failed due to housekeeper abuse.
I replaced them with comparable batteries from East Penn that were quite a bit less expensive than the Trojan.

What I have learned is that it is better to deal directly with a battery supplier that carries a wide range of batteries than an automotive parts retailer.
It has been my experience that auto parts retailers really do not have a good understanding of the different battery types.

The East Penn replacement is a DC27 battery for our Advance unit.
If you look at the spec sheet you will see that they have a "12-VOLT DUAL PURPOSE STARTING/DEEP CYCLE SERVICE" battery and a "12-VOLT MARINE/RV HEAVY-DUTY DEEP CYCLE SERVICE (INCLUDING STARTING)" available.
It is likely the first one that you got.
This is all interesting, Greg. If memory serves me now, the Trojan had a 27 number after it. What does that mean?: Does it mean it is good for 27 months? (for such applications?)

Now you said in your last sentence that I likely got the first one. The first one you list as deep cycle, without the marine word attached to it. Now did you mean that was the batteries I got that were the replacement ones? Or do you mean those were the original Trojan batteries?

Now get this? I did indeed get 2 new free batteries Friday. I called the janitor Saturday morning and he said that the new batteries worked! He got 2 1/2 hours straight run time out of them, and he would have gotten more but that is all he need-ed to run the machine for. He said the green indicator light was still on, when he parked it!

And that is with the new identical deep cycle marine. According to a prior post of yours, I was of the impression that the marine batteries may be the cause of my problem. But now, after you consider the good run time we are getting, does that change your opinion? Or - is the fact that they are the deep cycle marine type, that this will affect the longevity of the batteries, so that we can expect THESE batteries to lose run time the same way the other ones did? (We only got 10 1/2 months out of them when they went from 3+ hours run time down to 35 minutes run time.)

We do have a battery store in town. In lieu of your opinion about the deep cycle marine batteries, vs. just the deep cycle batteries, I think I will give the guys there a call. I'd really like to get to the bottom of this, so maybe I can help even educate the guys at our big tractor supply type/automotive shop store, where I bought those batteries. Remember -they had even advised me that they sell that very battery to others for floor scrubber machines. Maybe they have been selling the wrong batteries, to everyone, not knowing all there is to know?

I will also let you know what my hydrometer says on these newest batteries, after I get out to the building.

I really do appreciate your help on this subject.
 
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Old 03-08-09, 04:13 PM
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I meant that you have the marine starting/deep cycle dual purpose battery.
27 refers to the size of the battery as being bigger than the 24 series.

If you look at the pdf of battery specs I linked to you will see the battery types.
The first is "12-VOLT MARINE/RV STARTING CALCIUM MAINTENANCE-FREE" type.
The second is "12-VOLT DUAL PURPOSE STARTING/DEEP CYCLE SERVICE"
The third is "12-VOLT MARINE/RV HEAVY-DUTY DEEP CYCLE SERVICE (INCLUDING STARTING)"

If you look at the minutes reserve @ 23 amp draw you will see the dedicated deep cycle is slightly higher than the dual purpose battery.
The minutes reserve is the only capacity to consider when dealing with true deep cycle batteries as you should not start a vehicle with them.

What you do not see listed is the shorter life of a dual purpose battery if it is used exclusively on a deep cycle application.

If you dig around that East Penn site you will see dedicated scrubber batteries that do not list cranking amps in their specs.
The reason cranking amps are listed on the small deep cycle batteries is that they are the same size as auto batteries and can be found in a lot of general public applications like RV's and boats.
 
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Old 03-08-09, 04:42 PM
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Thanks again.

So then what if I compare the RC(reserve capacity) of the Johnson Controls battery and the Trojan battery?

And what do you make of the fact my Johnson Control batteries say they have 120 amp hour rating? (The original Trojans were 105). Is that good perhaps for the short term life of this dual purpose battery only?, but then becomes ineffective with age? (as obviously that happened with the first replacements.)

What would you do if you were in my shoes? Remember that the tractor supply store told us that they sell those batteries all the time for floor scrubbers. Do we run these 'til their run times get unacceptable as well? And THEN buy new ones like Trojans, at our expense? Or do we go back to the tractor supply-type store and lay this (your explanation)whole story on them and see if they will give us proper batteries at some kind of discount due to their mistake, and what we went through and may likely go through again?

What do you think is a decent price for the batteries we need?
 
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Old 03-08-09, 06:01 PM
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What batteries they sell for scrubbers all the time has nothing to do with what might be the correct battery!

The DC27 batteries I ordered were around $120.00 CDN ea.
What do you pay?

I think that if they replace the batteries for nothing it would not be worth the trouble hassling them over it.
It should buy you some time to research a better replacement.

Just for fun try calling a battery only supplier for info, not an auto or marine dealer who sell batteries to make a bit of extra cash.
 
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Old 06-13-09, 10:14 AM
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batt water

I would just like to add that if you have not had to add water to the batteries then you may want to check the charge rate of your charger a voltage reading is all good and well but if the charger is not putting out the proper amps then you will have a effect of a failing battery. Also you said that it is a true 24 volt system that means you are checking voltage across one battery. then the combined voltage would be 30 volts this is good but is the amps up to par, a spark at connection is going to happen if your meter reads voltage all the time even with key off or if the charger is alwayes connected . it would take a pretty good draw to effect performance. and if you have a volt meter on the unit while operating then when you operate the unit it should read about 20 , 21 volts if it reads any less then batteries are not up to par or charger is not charging properly don't get so caught up with the volts if you pay attention to the amps then you will locate the problem I believe you have a charging problem because you have not had to add water in 11 months common sence tells me that the charger is either a low rate charger or it is not working properly . if the amp rate is lower than it should be I would first test the scr's in the charger then the board because it could be reading the batteries incorrectly then the transformer. think about this you replaced batteries in the unit because you thought or was told they were bad but you still have a performance problem related to battery power. get it , now go fix it
 
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Old 06-14-09, 04:26 AM
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Sorry to come in late. but you are way over charging. You should never charge at more than 14.4v. When full after a 24 hour sit the batterys should read 12.6v if full at 21 centigrade. When they get to 12v they are empty. How far do you run them down? The optimum is so that the baterys have about 30% of capacity remaining.
 
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Old 06-14-09, 11:48 AM
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Originally Posted by GregH View Post
What batteries they sell for scrubbers all the time has nothing to do with what might be the correct battery!

The DC27 batteries I ordered were around $120.00 CDN ea.
What do you pay?

I think that if they replace the batteries for nothing it would not be worth the trouble hassling them over it.
It should buy you some time to research a better replacement.

Just for fun try calling a battery only supplier for info, not an auto or marine dealer who sell batteries to make a bit of extra cash.
Gee. I forgot to recheck this thread after my last post, Greg.

I think the batteries we got at the chain farm and barn store (those infamous combo marine/deep cell ones) were maybe about $70, each?

I know know that these indeed will hold an under full load charge of at least 3 hours, new, as the janitor said they ran the full 3 hours without ever stopping. Now that I have that benchmark, we will see what happens to these batteries down the road, as to how quickly once again this type of battery no longer holds charge but for say 1/2 hour (like the last time).

If this happens again after a years time, again, we will definitely go to the deep cycle only battery.
 
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Old 06-14-09, 11:59 AM
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Originally Posted by Charger repair View Post
I would just like to add that if you have not had to add water to the batteries then you may want to check the charge rate of your charger a voltage reading is all good and well but if the charger is not putting out the proper amps then you will have a effect of a failing battery. Also you said that it is a true 24 volt system that means you are checking voltage across one battery. then the combined voltage would be 30 volts this is good but is the amps up to par, a spark at connection is going to happen if your meter reads voltage all the time even with key off or if the charger is alwayes connected . it would take a pretty good draw to effect performance. and if you have a volt meter on the unit while operating then when you operate the unit it should read about 20 , 21 volts if it reads any less then batteries are not up to par or charger is not charging properly don't get so caught up with the volts if you pay attention to the amps then you will locate the problem I believe you have a charging problem because you have not had to add water in 11 months common sence tells me that the charger is either a low rate charger or it is not working properly . if the amp rate is lower than it should be I would first test the scr's in the charger then the board because it could be reading the batteries incorrectly then the transformer. think about this you replaced batteries in the unit because you thought or was told they were bad but you still have a performance problem related to battery power. get it , now go fix it
Thanks. I have no reason to suspect anything is (was, actually - as the machine has now been working fine for the last several months) wrong with the onboard charger or any of the digital printouts that it gives.

It is like a computer and does a preread of like 5 functions, then gives status as it is being charged. The amps finally come down to 0.00 A after it gets charged. If the charger was at fault, I think that now after the new batteries have been put in, that we'd be having problems by now. But we haven't.

I think that SM Greg has it right about the fact the machine would be better served to have deep cycle only, batteries, without that compromising marine business thrown into the mix. The machine actually came equipped with Trojan deep cycle batteries, that are more expensive from the specialty equipment shop, than the marine/deep cylce batteries are at the chain store.

Here, duie to my lack of knowledge (and theirs too!), **I** presumed that the marine type would be a good thing. I always thought marine ANYTHING equated to top of the line. Such as marine plywood, glue, etc.
 
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Old 06-14-09, 12:03 PM
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Originally Posted by 07bloomfieldb View Post
Sorry to come in late. but you are way over charging. You should never charge at more than 14.4v. When full after a 24 hour sit the batterys should read 12.6v if full at 21 centigrade. When they get to 12v they are empty. How far do you run them down? The optimum is so that the baterys have about 30% of capacity remaining.
As a maintenance man, I actually do not charge enough!

Without rereading this entire long thread.........where was this indicated?
 
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